// 验证对称 比较同层 并递归当前
var isSymme = function(root){
    if(!root) return root;
    return isSame(root.left, root.right)
}

function isSame(leftNode,rightNode){
    if(leftNode == null && rightNode == null) return true
    if(leftNode == null || rightNode == null) return false
    return leftNode.val === rightNode.val && isSame(leftNode.left,rightNode.right) && isSame(leftNode.right , rightNode.left)
}